The invention relates generally to a process of and apparatus for extruding materials onto a preform and more specifically of extruding dissimilar plastic materials onto a weatherstrip preform and the resulting product.
Most motor vehicles are equipped with movable windows that slide in a window opening from an up or extended position that seals off the opening to a down position, retracted within a door, that opens all or a portion of the opening and allows, among other things, an exchange of air between the inside and outside of the vehicle. A sealing device broadly referred to as a weatherstrip is disposed about the periphery of the window opening and provides an air and watertight seal between the vehicle body and the window. The interface between the door and the movable window at the lower extremity of the window opening is typically equipped with a weatherstrip denominated a beltstrip which serves both as aesthetic and mechanical functions. Aesthetically, it hides the interface. Mechanically, it provides a wiper flange or blade for cleaning the window as the window extends and retracts from the vehicle door.
Recently, emphasis has been placed upon vehicle streamlining in order to reduce both aerodynamic drag and wind noise. To achieve these goals, design considerations such as the elimination of all gaps and channels, the reduction of profile configurations, the overlapping of the beltstrip or weatherstrip on the glass, as well as installation ease, serviceability and durability have greatly increased significance. Attainment of such goals depends upon the satisfaction and proper balancing of such design considerations.
Beltstrips and weatherstrips are often extruded or roll-formed in a complex manufacturing process having several steps. Typically, a core metal structure is formed and coated with an extruded layer of synthetic elastomeric material to form a belt molding and then is cut to length. A sealing strip having a flexible blade for contacting the window may be formed and coated in an extrusion process. The sealing strip is then affixed to the belt molding. The belt molding and the sealing strip are usually notched at spaced locations. Clips are then inserted into the notches to connect the belt molding and the sealing strip. The clips also grip an upright edge formed on the door of the vehicle to hold the beltstrip on the door.
Manufacturing and aesthetic flexibility drive the newest beltstrip and weatherstrip products. For example, it is frequently required that a beltstrip be fabricated of distinct plastic or elastomeric parts, such distinct parts display different resiliencies. Moreover, of equal or greater importance is the ability to respond to varying aesthetic requirements. For example, it is now frequently required that weatherstrips include color keyed, i.e., matching or contrasting, color inserts keyed to vehicle body color. Additionally, a specific weatherstrip may include bright work when installed on a vehicle at a certain trim level, whereas at a lower trim level, bright work will not be utilized. A standardized beltstrip which may be modified or augmented to satisfy varying color and trim design would thus be desirable. The present invention is directed to such a product.